1. Field of the Invention
The present invention relates to the production of alterable tones in a musical tone synthesizer.
2. Description of the Prior Art
An electronic organ characteristically is capable of a large number of tonal variations produced by adding a set of preselected tones in all possible combinations. For example, if a given keyboard has 6 stops, or preselected tones, a total of 63 combinations is possible. In spite of this apparent large variety, musicians are constantly seeking new and distinctive tones with which to play particular music.
The Hammond organ introduced about 40 years ago provided a set of 9 drawbars for varying the tone of a keyboard. The system of drawbars has been widely used and even today new organs are designed using this method of obtaining tone variation. A limitation of the drawbar system is that only 9 harmonics are provided which do not suffice for very "bright" tones which may contain about 32 harmonics. Abortive attempts have been made to increase the number of drawbars. However, a set of 32 individual harmonic level controls is beyond the technical and mechanical ability of the average musician. It is both difficult and extremely time consuming to set 32 individual controls.
Organs have been built wherein an alterable voice is provided by reading waveshape data punched on a computer card. This system suffers from requiring computer generated data which requires technology beyond the capability of the musician.
It is an object of the present invention to implement an alterable voice in a tone synthesizer type of musical instrument employing stored sets of harmonic coefficients to generate tones.
Another object is to introduce new sets of harmonic coefficients encoded by imprinting opaque areas on a transparent data card, the encoding employed being readily interpreted as the harmonic spectra of a musical tone.